JP6306510B2 - High temperature or fuel cell electrochemical system with improved thermal management - Google Patents

Description

  The present invention relates to electrolyzers and fuel cell stacks that operate at high temperatures with improved thermal management.

The high-temperature electrolytic cell is usually referred to as SOEC (solid oxide electrolysis cell). They achieve an electrochemical conversion from electrical and thermal output to chemical energy. The term “co-electrolysis” means an operation in which a mixture of steam and carbon dioxide, H ₂ O / CO _2, is supplied to the electrolytic cell. Steam is transformed into hydrogen, and carbon dioxide is transformed into carbon monoxide, which acts as an energy carrier. Depending on requirements, these H ₂ / CO flammable gases can then be converted to heat and electricity using, for example, a stack of SOFCs (solid oxide fuel cells).

The SOEC electrolytic cell and the SOFC fuel cell stack represent the reverse operation of the same electrochemical system.
It should be noted that these systems are very electrically efficient. Furthermore, great flexibility regarding the nature of the fuel is possible in the SOFC mode. The stack can for example be directly supplied with neutral gas. In this case, the reforming of methane to hydrogen occurs directly in the system cell.

  The subject SOEC electrolyzer and SOFC fuel cell stack is formed by a stack of many flat ceramic cells in which an electrochemical reaction takes place, and generally an interconnect plate interposed between each pair of ceramic cells. Is done. The cell has on each of its faces a ceramic layer that constitutes the electrodes (anode and cathode), where the two electrodes of a given cell are insulated and separated by a ceramic membrane that acts as an electrolyte.

  The interconnect plate distributes gas to each of the two electrodes of the cell and collects current. In the stack, the interconnect plates are structured on both sides to perform current collection and distribution functions for opposing electrodes of two consecutive cells located facing each other.

  The assembly between one cell and the two interconnect plates surrounding it forms a defined basic unit. In particular, the basic unit comprises a cathode part (position where the chemical species are reduced) and an anode part (position for the oxidation reaction), which are two volumes that are sealed and electrically isolated.

  Heat transfer takes place in part by the gas and by heat exchange between the end of the stack and its insulating coating. It is understood that the hottest possible basic unit allows the exchange surface to be increased and facilitates thermal management of the system. However, interconnect plates are usually made of pressed plates made as thin as possible to improve the miniaturization of electrochemical converters and reduce costs. Therefore, it seems important to find a compromise between this limitation of miniaturization that gives a small volume and heat exchange that requires a large area.

  With respect to steady state operation, thermal management of the SOFC stack exists in part by adjusting the flow rate of air sent to the cathode. Further, internal reforming facilitates thermal management of the stack, since the endotherm of the chemical reaction that transforms methane to hydrogen tends to balance the heat release caused by the electrochemical oxidation of hydrogen. However, during a transient load or within a phase when the system is switched on / off, a temperature gradient can appear and cause mechanical damage to the stack.

  With regard to SOEC thermal management, depending on the operating voltage, the heat released by the operating reverse battery protection may be less than, equal to or greater than the heat absorbed by the steam electrolysis. It is shown. For high steam change rates, the temperature of the electrolyzer changes very rapidly to a level that is unacceptable for long term operation of the system. In fact, when operating in the exothermic mode, the hydrogen produced will contain little heat. Therefore, the flow of hydrogen released by the electrolytic cell cannot discharge a large amount of heat. It should be mentioned that in the case of endothermic operation it can prove difficult to provide heat to the stack for optimal operation.

  As a result, an object of the present invention is to provide an electrical appliance such as a high temperature electrolyzer or fuel cell with improved thermal management that provides high flexibility with respect to thermal management of the system, whether steady state control or transient operation. To provide a chemical system.

  The above objective is in a stack of basic units formed by ceramic cells and interconnect members, by radiation, which is significantly larger than the surface of the interconnect members, providing a radiating surface between the stack and, for example, a thermally kinetic coating. This is achieved by inserting a plate having a surface for heat transfer.

  This fairly large radiating surface is obtained by structuring the lateral surface of one or more radiating plates. These plates are preferably distributed in the stack periodically. They can be located as replacements for a particular interconnect member, or can be located adjacent to an interconnect member, when the particular interconnect member is manufactured to provide a gas supply for a cell.

  The term “structured” is understood to mean creating undulations on the surface of the plate so as to increase the heat exchange surface of the plate, which undulations are in the form of ribs forming eg fins. Further, the term “heat transfer” in this application is understood to mean the transfer of heat from the stack to the outside, but also means to transfer heat from the outside to the stack in the endothermic mode of operation.

According to the present invention, since the emitted flow is proportional to T ^4, the radiant heat exchange by the emitted flow, much higher than that temperature. Therefore, this heat transfer mode is low at ambient temperature and becomes dominant at the operating temperature of the SOEC type or SOFC type electrolytic cell. In particular, it is very suitable for SOEC type electrolysers and SOFC stacks.

  In particular, in an advantageous embodiment, the radiating plate comprises a lateral head projecting from the stack; then, in addition to the lateral surface, the surface of the head perpendicular to the axis of the stack can be structured.

  These plates are preferably thicker than the interconnect members and provide even larger radial lateral exchange surfaces.

  The stack is divided into subunits of cells that are surrounded and separated by plates that effectively cause transmission by radiation. These plates are responsible for transmission by radiation function. In prior art electrolysers and cell stacks, transmission by radiation occurs at the end of the interconnect member, which is very thin.

  These plates are particularly efficient in stack thermal management, where heat transfer by radiation is the dominant method of heat transfer and is the most efficient method in stacks of fuel cells and electrolyzer cells.

  Furthermore, they enable particularly suitable thermal management of systems that require greater flexibility, for example in terms of reversibility, transient operation, injection gas diversity.

  A main object of the present invention is an electrochemical system comprising a stack of longitudinal shafts having alternating ceramic cells and interconnect members, and thermal management means included in the stack, wherein the thermal management means comprises the stack Comprising at least one plate located in the stack, referred to as a “radiating plate”, having at least one lateral end having a surface in which heat exchange is performed by radiation with the outside of the surface, An electrochemical system characterized in that it is at least partially structured.

  The radiating plate is thicker than the interconnect member, the interconnect member may be 0.1 mm to 15 mm thick, and at least one radiating plate is 5 mm to 50 mm thick.

  In a particularly advantageous embodiment, the radiating plate has a cross section that is larger than the cross section of the cells and the cross section of the interconnection member, which has a peripheral head protruding from the stack, The head has a lateral end whose surface is at least partially structured.

  The head has two longitudinal faces, at least one of which is partially structured.

The surface of the lateral end and / or at least one longitudinal surface is advantageously coated with a material having an emissivity close to 1, for example Pr ₂ NiO _{4 + δ} .

  The electrochemical system can include a number of radiating plates distributed throughout the stack. The radiating plate is periodically distributed in the stack, for example distributed every 4 to 12 basic units, the basic units being formed in a ceramic cell and two interconnect members. According to an advantageous feature, the one or more radiating plates distributed periodically in the stack replace the interconnection members located at the end of the basic unit assembly from which they separate.

  The electrochemical system may include a circuit that supplies an electrolytic gas to the ceramic cell.

  The radiating plate can also include means for heat transfer by convection. The means for heat transfer by convection may be formed by a flow path formed in the radiating plate and extending substantially in the plane of the plate through which fluid flows. The fluid may be a fluid different from a fluid used in the electrochemical-based electrolysis reaction or an electrolytic gas used in at least one of the electrochemical-based electrolysis reactions, Means for connecting the flow path to an electrolytic gas supply circuit;

  The electrochemical system according to the present invention can be a fuel cell that operates by reforming in neutral gas, where the flow path is coated with a steam reforming catalyst and the fluid is a neutral gas.

  The radiating plate may include means for heat transfer by convection.

  The radiating plate may include a material that changes phase at the desired operating temperature of the system. The amount of phase change love is arranged, for example, in a cavity.

  The phase change locus sample may be a eutectic material having a solidus temperature close to 800 ° C and a liquidus temperature close to 850 ° C.

  Alternatively, the phase change material can be a molten salt, such as NaCl.

  In an advantageous example, the at least two radiation plates have electrical connections that can electrically insulate cells located between the two radiation plates.

  The electrochemical system according to the present invention can be, for example, a high-temperature electrolytic cell for producing hydrogen.

  The electrochemical system according to the present invention can be a fuel cell in which consumed hydrogen can be produced by steam reforming of neutral gas.

FIG. 1A is a top perspective view of a first embodiment of a thermal management plate. FIG. 1B is a detailed view of a side end of the radiation plate of FIG. 1A. FIG. 1C is a front view of an embodiment of a stack including the thermal management plate of FIG. 1A. FIG. 2A is a side perspective view of a modified embodiment of the first embodiment of the thermal management plate. 2B is a cross-sectional view taken along the plane AA of the radiation plate of FIG. 2A. FIG. 2C is a front view of an embodiment of a stack including the thermal management plate of FIG. 2A. FIG. 3A is a top perspective view of two thermal management plates according to a second embodiment including conduction type transmission. 3B is a cross-sectional view of the upper plate of FIG. 3A along the BB plane. FIG. 4A is a top perspective view of two heat management plates according to a modification of the second embodiment. 4B is a cross-sectional view of the upper plate of FIG. 4A along the CC plane, as seen from the side edge located on the back side of FIG. 4A. FIG. 5 is a top perspective view of a part of a stack of a high-temperature electrolytic cell according to the present invention including a heat management plate according to another modification of the second embodiment. FIG. 6A is a top perspective view of a heat management plate according to another modification of the second embodiment. 6B is a cross-sectional view of the plate of FIG. 6A along the DD plane. FIG. 7A is a top perspective view of a thermal management plate according to a third embodiment using a phase change material. FIG. 7B is a cross-sectional view of the plate of FIG. 7A along the EE plane. FIG. 8A is a perspective view of a stack including a thermal management plate according to an alternative embodiment. 8B is a cross-sectional view of the stack of FIG. 8A along the FF plane. FIG. 9A is a perspective view of a stack including a thermal management plate according to an alternative embodiment. FIG. 9B is a perspective view of a stack including a thermal management plate according to an alternative embodiment.

  The present invention will be understood in detail with reference to the detailed description that follows and the accompanying drawings.

  In FIG. 1C, an embodiment of a stack according to the invention for an electrochemical system such as a high temperature electrolyzer or a fuel cell can be seen.

  The stack includes ceramic cells 2 extending along the long axis X and separated by interconnect plates 4 or interconnect members. The assembly A is formed by one cell 2 and two interconnect plates 4 surrounding it, forming a basic unit. These cells are made of an electrolyte (typically yttria-doped zirconia, or yttria stabilized zirconia (YSZ) surrounded by two electrodes), one of which is a perovskite structural material (lanthanum strontium). Made of manganite (LSM), the other of the electrodes comprises a ceramic-metal composite (made of a mixture of YSZ and nickel (Ni-YSZ)), and can be, for example, a multilayer ceramic structure. The connecting member is typically made of Crofer® 22 APU alloy, which is a ferritic steel that is Haynes 230®, or a nickel-based alloy.

  As an example, the composition of Crofer® 22 APU and Haynes 230® is listed in the table below.

  The stack also usually includes additional plates. The plate 6 is made of a conductive material, preferably a metal, such as Crofer 22 APU® ferritic steel or F18TNb. These plates 6 provide thermal management of the electrochemical system by heat transfer by radiation of heat generated when the electrochemical system is operated. The plate 6 is hereinafter referred to as “radiating plate”.

  The plates 6 are preferably distributed in the stack periodically. For example, the two radiating plates are separated by 4 to 12 basic units. The number of basic units separating the two radiating plates 6 is selected to limit the temperature gradient in the stacking direction, ie the current direction.

  The stack according to the invention comprises basic elements consisting of ceramic cells and interconnecting members and a radiating plate: As shown below, the radiating plate can also function as an interconnecting member; however, they are part of them. To replace.

  An exemplary plate 6 is shown in FIG. 1A and a detailed view thereof is shown in FIG. 1B.

  In the example shown, the radiating plate 6 has a square shape and thus has four lateral ends 8 that form an exchange and heat transfer surface.

  The plate 6 has a surface for heat transfer by radiation that is larger than the surface of the interconnection member. The plate 6 has a lateral end 8 that is at least partially configured to increase the radiating surface. In FIG. 2A, an example of such a plate 6 having such a structure can be seen. In FIG. 1B, an enlarged view of the side edge 8 of the plate of FIG. 1A can be seen. In this example, the end 8 has a rib 9 parallel to the longitudinal surface of the radiation plate, which rib has a V-shaped cross section. Rib alignment is not limiting. In particular, ribs extending perpendicularly or obliquely to the longitudinal plane of the plate do not depart from the scope of the present invention. Furthermore, the structural unit can be of any kind and can vary from end to end.

  The lateral edges of the plate can be in the same vertical plane as the lateral edges of the stack, and the tops of the ribs lie in these vertical planes. As a variant, the structure of the side ends protrudes and the top of the rib protrudes from the vertical plane of the end of the stack.

  The radiating plate preferably has a thickness that is greater than or equal to the dimension of the interconnect member, ie, a dimension along the longitudinal axis X. They have a heat exchange surface for the structure of their lateral surface that is larger than the lateral surface of the interconnect member.

  The following gives advantageous thickness values for the interconnect and radiating plates.

  In the case of “thin” interconnect plates, such as those manufactured with pressed plates, this plate can be 0.1 mm to 1 mm thick, and the radiating plate is preferably 10 mm to 50 mm thick The thickness is preferably 40 mm.

  In the case of a “thick interconnect plate”, it can be 5 mm to 10 mm thick and the radiating plate is advantageously 5 mm to 20 mm thick, preferably 10 mm thick.

  The plate 6 of FIG. 1A has a surface that is substantially equal to the interconnect member 4 and the cell 2, ie, its ends are approximately aligned with the surfaces of the interconnect member and the cell.

  In the example shown, the radiating plate 6 can replace an interconnect member located at the end of a continuous stack of basic units; one of the longitudinal faces 10 of the radiating plate is a combustion gas and an oxidizing gas Has a flow path for supplying to the cell. This arrangement can simplify the stack and reduce electrical resistance and sealing problems.

  Alternatively, the plate 6 can be located between the cell 2 and the interconnect member, and drilling can be done to form a fluid connection through the stack.

  2A and 2B, a particularly advantageous variant embodiment of the radiating plate 106 according to the invention can be seen, in which the plate 6 has a structure on the outer periphery of its lateral end 8 and its longitudinal surface 10.

  Plate 106 has a cross-section that is larger than the cross-section of the cells and interconnect members, which has an outer circumferential head 111 that projects from the central lateral surface of the stack. In FIG. 2C, a stack including the plate 106 can be seen; the protruding head 111 of the radiating plate 106 forms a heat exchange fin.

  The longitudinal surface of the head 111 has the structure of its lateral ends 108 in the same manner as the plate 6, and advantageously has the structure 113 of its longitudinal outer end 112. As seen in FIG. 2B, this structure 113 seen in cross section has the shape of a saw tooth. The tooth maximum surface 113.1 preferably faces the outside of the stack, the side surfaces face the outside and the heat is mainly released to the outside.

  Alternatively, it can be determined that only the longitudinal surface has a structure and the side edges are smooth, or conversely, only the side edges are structured and the longitudinal surface is smooth. Partial structuring of the side edges and / or longitudinal faces can also be envisaged.

  Further, the square shape of the plate, more generally the elements of the stack, is not limiting, for example, the disc shape does not depart from the scope of the present invention.

  As an example, the dimensions of the plate are described.

1.5 volts for a cell with an active surface of 77.44 cm ² , a radiating plate located every five cells, a 1 mm thick interconnect member, a gas injection temperature, and a thermalization of the coating surrounding the stack at 800 ° C. Assuming that the applied voltage is applied, the structured heat radiating plate 6 has a thickness of 44 mm. For an interconnect member that is 10 mm thick, the structured radiating plate is 11 mm thick.

  The thickness of the radiating plates depends on the degree of structuring of their lateral ends and in some cases on the degree of structuring of the longitudinal surfaces.

The lateral and / or outer edges of the radiating plate can be advantageously coated with a material having an emissivity close to unity. For example, the coating can be Pr ₂ NiO _{4 + δ} obtained by the pyrosol method.

  It is also conceivable to increase radiation loss by this means for cooling the stack by controlling the environment outside the stack, for example the temperature of the coating surrounding the stack. In these situations, direct control of the electrolyzer or fuel cell temperature can be obtained. Similarly, in endothermic mode, the transfer of heat in radiant form is facilitated by producing the temperature of the outer coating.

  In the example, the central planar side edge is generally parallel to the longitudinal axis X of the stack; however, these planes can be inclined with respect to the longitudinal axis.

  As a variant, it can be decided to form an outer lateral head that is thicker than the central part of the radiating plate, which increases the radiation loss by this means; this thickened head can also be structured.

  An alternative embodiment of the radiation plate 506 can be seen in FIGS. 8A and 8B. In this variation, the radiating plate includes a protruding peripheral head 511, whose lateral ends 508 have undulations 509. In the example shown, these undulations 509 have an axis parallel to the axis of the stack. The radiating surface is increased by this means.

  9A and 9B are other alternative embodiments of the radiating plate 606, which are that the surrounding head 611 is thicker than the cross-section of the portion of the radiating plate located in the stack. Different from 8B radiation plate. As can be seen in FIG. 9B, the head 611 around the radiating plate has an approximately T-shaped shape. The side end 608 also has undulations 609. The radiating surface is further increased. Other shapes that generate increased radiating surfaces are conceivable, for example L-shaped shapes.

  3A and 3B, a second embodiment of a radiating plate according to the invention can be seen, which includes cooling by convection in addition to cooling by radiative transfer. Conversely, in endothermic mode, these changes due to convection allow heat to transfer to the stack.

  The plate 206 shown in FIGS. 3A and 3B is also for forming an interconnect member. In FIG. 3A, cells and interconnect members are omitted.

  In FIG. 3B, a cross-sectional view of the plate 206 through section CC can be seen. A radiating plate 206, such as plates 6 and 106, has at least a portion of its lateral end 208 structure to provide cooling by radiative transfer and means to provide heat transfer fluid to flow therein. And cause heat exhaustion by convection. In the example shown, the flow inducing means is formed by a channel 216 extending between the ends 208 of two parallel plates 206 that are parallel to each other. The flow path 216 is connected to the supply connector 218 at the first end, and is connected to the discharge connector 220 at the second end. In this embodiment, the channels 216 are provided in parallel and all plates 206 are fed in parallel by a tube 222 connected to a connector 218 that feeds all the plates 206 to retract all the plates 206. They are retracted in parallel via a tube 224 connected to the connector 220. The heat transfer channel can be arranged in any manner.

  In this example, the heat transfer fluid is a different gas than that used in electrolysis when the cell stack or cell is in operation. This gas is, for example, a neutral gas that flows to the radiating plate 206 that recovers any excess heat generated.

  There is an electrical insulator between the radiating plates 206. For example, the electrical insulator is formed at the junction between the tube 222 and the supply connector 218 using, for example, a mica seal.

  4A and 4B, a variation of the system of FIGS. 3A and 3B where the heat transfer channel 216 is connected in series can be seen. The heat transfer fluid supply pipe 222 supplies the supply connector 218.1 of the first plate 206.1 of the stack, and the discharge connector (not visible) of the first plate 206.1 follows the supply of the plate 206.2. Connected to connector 218.2, etc., heat transfer fluid flows through all plates.

  In the example shown, the plates 206 are for replacing the interconnect members; they also have a flow path 226 for supplying oxidizing gas and fuel gas at their center. The channel 226 itself is supplied via a branch connector 230 located at the end of the plate and a channel formed inside the plate 206.

1.5 V / cell applied voltage, cell with an active area of 77.44 cm ² , radiation plate 206 located every 5 cells, stack temperature not exceeding 840 ° C., introduced at 800 ° C. at a flow rate of 2 l / min In a system having a flow and an interconnect member thickness of 1 mm, the thickness of the radiating plate 206 was determined to be about 42 mm. The distribution of heat dissipated in the stack is as follows: about 70.5% of the heat is exhausted by radiation loss, 27% of the heat is exhausted by the cathode and anode fluid, and 2.5% is heat. It is discharged by the transmission fluid. Thus, convective cooling allows the stack thermal management to be improved by additional cooling by radiative transfer. For example, by increasing the fluid flow rate or selecting a more efficient heat transfer fluid, the amount of heat dissipated by convection can be increased.

  An alternate embodiment of the plate of FIGS. 3A-4B is seen in FIG. 5 where the convective cooling means uses anode and cathode electrolytic gases.

  In FIG. 5, a stack of radiating plates 206.1 ', 206.2', 206.3 'and cell 2 is shown. The radiating plates 206.1 ′, 206.2 ′, 206.3 ′ are similar to the radiating plates 206 of FIGS. 3A-4B, and the pipe 222 is radiating plates 206.1 ′, 206 shown in series in the example. .2 ′, 206.3 ′ are supplied with electrolytic gas. At the outlet of the plate 206.3 ', the collected electrolytic gas is injected into the cell 2 by the pipe 234 via the lateral branch connection of the first plate 206.1. Arrows indicate gas flow. The electrolytic gas is, for example, steam. The fluid connection connecting the two radiating plates has an electrical insulator realized, for example, using a mica seal.

  Due to this arrangement, the stack is cooled by convection and the electrolytic gas is preheated at the same time using directly the heat generated close to the cell.

  According to another variant, it is conceivable for the gas to also flow around the stack located in its coating in order to facilitate convective exchange.

  In another variation shown in FIGS. 6A and 6B, in the case of a cell stack SOFC operating in the reforming mode of methane, the flow path 316 of the radiating plate 306 is doped, for example, Ru−, Rh− (or other). The ceria type steam reforming catalyst 336 is covered. With this measure, the neutral gas is pre-reformed before it is introduced into the fuel cell. Since this reaction is endothermic, it cools the stack by convection.

  During operation, the electrochemical system can be exposed to voltage and thermal cycles. These transitions cause temperature gradients that are detrimental to the mechanical integrity of the cell. Furthermore, very high temperatures, temporarily above 850 ° C., can damage the metal material of the stack.

  The example radiating plate embodiment shown in FIGS. 7A and 7B advantageously allows abrupt changes in temperature in the stack, which is a temperature above 850 ° C., to be limited.

  As in the second embodiment, the radiating plate 406 includes a channel 416 that includes a channel 416 that is parallel to each other and that extends between two parallel ends of the plate 406. However, these flow paths include a phase change material 438 whose phase changes between 800 ° C. and 850 ° C., which is within the operating temperature range of the electrolysis and high temperature fuel cell stack. The latent heat required to transform the phase change material 438 is supplied by the heat generated by electrolysis; therefore, this heat is absorbed by the phase change material 438 and limits temperature rise above a dangerous threshold for the stack. To do.

  The phase change material 438 can be a eutectic mixture that melts at a constant temperature and allows the stack to be maintained at a constant temperature during this phase change. For example, it may be an alloy having a solidus temperature close to 800 ° C and a liquidus temperature close to 850 ° C. This eutectic mixture material can be, for example, an Ag (96.9%)-Si alloy having a melting point of 835 ° C, or it can be Cu-Si (85%) having a melting point of 802 ° C, or 848 It can be LiF with a melting point of ° C., and in lower temperature applications it can be Ag—Cu (28%) with a melting point of 780 ° C. Ag58-Cu32-Pd10 (853 ° C to 824 ° C), Au60-Cu20-Ag20 (845 ° C to 835 ° C), or Ag95-Al5 (830 ° C to 780 ° C) or Ag68-Cu27-Pd5 (814 ° C) at lower temperatures Other alloys such as ~ 794 ° C) are expected. The solidus temperature or the liquidus temperature is each given between the brackets.

Phase change material 438 may also be a less costly molten salt. If molten salt is used, the radiating plate must be protected from corrosion, for example by boron nitride. For example, NaCl having a melting point of 800 ° C. or Na ₂ Co ₃ having a melting point of 850 ° C. can be used as the molten salt. By using NaCl as the phase change material of the radiating plate according to every fifth module of the present invention, a temperature of 800 ° C. is achieved for 30 minutes by filling 10 channels with a diameter of 10 mm and a length of 200 mm. Can be guaranteed at .5V. For the calculation, an output of 100 W discharged, a latent heat of NaCl of 472 kJ / kg, and a density of 2160 kg / m ³ are considered.

  Due to the use of phase change materials, upper and lower thresholds can be introduced into the stack temperature to limit large temporary temperature changes called transient changes.

  In search of optimization of hydrogen generation according to the cost of electricity, this electricity is used to operate at a high potential (1.5V) when the electricity bill is low and to use the heat released to melt the alloy. Decisions can be made regarding the system. Then, if the electricity bill is high, the electrolytic cell operates at a lower voltage of 1.3V in the endothermic mode. The heat stored by the phase change material then returns to the stack as it solidifies, providing an available heat source that increases the efficiency of the electric field.

  In the example shown in FIGS. 3A-7B, the channels are linear and parallel to each other, but this shape is not limiting and is distributed in several layers and / or non-uniform on the plate Bent channels and / or any other shape channels distributed in a manner do not depart from the scope of the present invention.

  A radiating plate having a flow path can be manufactured by powder metallurgy using a hot isostatic pressing (HIP) process.

  In this case, the assembly forming the distribution channel is obtained by a curved metal tube surrounded by the material forming the plate pre-introduced in powder form. This assembly is pressed at a high temperature to obtain a dense part and its outer surface can be well formed by machining to obtain the final dimensions. As a variant, it is decided to form the flow path by performing a first series of drillings in parallel, followed by a second series of two drillings perpendicular to the first series of drillings, It is like a series of drilling holes communicating with each other. The discharge area is then closed, for example by welding a cylindrical plug having the dimensions of the hole. This modification is more advantageous in cost than the HIP method.

  According to other embodiments not shown, cooling by convection is combined with cooling by radiative transfer. For example, the stack is housed in a thermally conductive coating, and the radiating plate has a cross-section that is larger than the cross-section of the cells and interconnect members, such that they contact the coating; Thermally connected. Some of the heat generated in the stack is exhausted by convection through the radiating plate and coating, and its temperature can be controlled. In this embodiment, an electrical insulator is provided between the radiating plate and the coating to prevent a short circuit between the radiating plates.

  Combinations of the modified embodiments described above do not depart from the scope of the present invention. For example, a radiating plate that includes a flow path through which a neutral gas that provides additional cooling by convection flows and an electrolytic gas that provides additional cooling by convection is heated and that includes a phase change material is It does not depart from the scope of the invention. Any other combination is possible.

  In addition to enabling simplified thermal management of the stack, the radiating plate can also allow the rest of the stack to be isolated if this part of the cell fails. To achieve this, the radiating plate can be adapted to the individual electrical connection members. It is always possible to provide a bridge by connecting two plates located at each end of this part. This simple operation allows this region of the stack where one of the cells is damaged to be electrically isolated. The stack can then continue to operate while avoiding current crossing the damaged cell.

  Finally, even in the absence of phase change material, the radiating plate causes a specific thermal inertia in the stack, thereby limiting the appearance of high excessive temperature gradients.

  In the case of a high temperature electrolytic cell, the present invention allows the electrolytic cell to be avoided from being exposed to large heat and allows it to operate at high vapor conversion rates.

  With the present invention, the thermal properties of high temperature electrolysers and fuel cell stacks can be managed efficiently and relatively simply. The means used, i.e. the radiating plate, also has a high operational safety and a great flexibility with respect to the cooling modes that can be implemented. Similarly, these plates can be used to provide the heat required in the endothermic mode of operation.

2 cells 4 interconnecting members 6 radiation plate 10 longitudinal surface 11 peripheral head 106 radiation plate 206 radiation plate 216 flow path 306 radiation plate 406 radiation plate 416 cavity 438 phase change material

Claims (15)

Stacked cell or fuel operating at high temperatures, comprising a stack of longitudinal axes (X) having alternating ceramic units (2) and interconnecting members (4), and thermal management means contained in said stack An electrochemical system that is a battery ,
A plate located in the stack, referred to as a “radiating plate”, wherein the thermal management means has at least one lateral end with a surface where heat is exchanged by radiation with the outside of the stack ( 6, 106, 206, 306), wherein the surface is at least partially structured, the radiating plate replaces some of the interconnect members, and the other interconnect member is the radiating plate Electrochemical system characterized by being separated from   The radiating plate (6, 106, 206, 306) is thicker than the interconnect member, the interconnect member (4) is 0.1 mm to 15 mm thick, and at least one radiating plate (6, 106, 206). 306) is a thickness of 5 mm to 50 mm.   The radiating plate (106) has a larger cross-section than the cross-section of the cell (2) and the cross-section of the interconnect member (4), which has a peripheral head (11) protruding from the stack. The electrochemical system according to claim 1 or 2, wherein the electrochemical system has a structure.   Said peripheral head (11) has a lateral end whose surface is at least partially structured and two longitudinal surfaces whose at least one longitudinal surface is partially structured ( The electrochemical system according to claim 3, comprising 10). The electrochemical system according to claim 4, wherein the surface of the lateral end and / or at least one longitudinal surface is coated with P r ₂ NiO _{4 + δ} . The radiation plate (6,106,206,306) is periodically distributed to the stack, basic unit is formed in the ceramic cell (2) and two interconnected members (4), according to claim 1 The electrochemical system according to any one of 1 to 5.   The electrochemical system according to any one of claims 1 to 6, wherein the side end portion has undulations.   The electrochemical system of claim 3, wherein the peripheral head is thicker than a portion of the radiating plate located in the stack.   The radiating plate (206) includes convective heat transfer means formed in the radiating plate (206) and formed by a flow path extending generally in a plane thereof, wherein fluid flows into the flow path. The electrochemical system according to any one of 1 to 8.   The electrochemical system according to claim 9, wherein the fluid is a fluid different from a fluid used for an electrolysis reaction of the electrochemical system.   10. The fluid of claim 9, wherein the fluid is an electrolytic gas used for at least the electrolysis reaction of the electrochemical system, the system including means for connecting the flow path (216) to an electrolytic gas supply circuit. Electrochemical system.   12. Electrochemistry according to any one of the preceding claims, wherein the radiating plate (406) comprises at least one cavity (416) comprising a material (438) that changes phase at a desired operating temperature of the system. system. The electrochemical system of claim 12, wherein the phase change material (438) is a eutectic material having a solidus temperature of 780C to 835C and a liquidus temperature of 814C to 853C. The electrochemical system of claim 12, wherein the phase change material is a molten salt .   15. Electrochemical system according to any one of the preceding claims, wherein the at least two radiating plates comprise electrical connections such that cells located between the two radiating plates can be electrically isolated. .

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